Heat exchanger



,A Mfrs 2 Sheets-Sheet 1 I. LUNDGAARD HEAT EXCHANGER Filed March 3o, 1922' April 21, 1925.

. l. LUNDGAARD HEAT EXCHANGER Filed March 50. 1922 2 Sheets-Sheet 2 u IN VENTO/ fla/wv Amiga/Mad.

@af/jf@ 20 Patented Apr. '21, 1925.

UNITED STATES PATENT OFFICE.

IVAR LUNDGAARD, OF HARTFORD, CONNECTICUT, ASSIGNOR TO THE AUTOMATIC 4 REFRIGERATING COMPANY, OF HARTFORD, CONNECTICUT, A CORPORATION 07F NEIN JERSEY.

HEAT ExcrLANGER.

, Application led March 30, 1922. Serial N0. 548,219.

the air is expandedf" Between these two' chambers the air is passed through a heat exchanger for transferring heat from the compressed air to a body of cooling fluid, a regenerator for maintaining a difference of temperature between the air entering it and the air leaving it and a heat exchanger for transferring heat from a fluid to be cooled. to the expanded air. In `my Patent No. 1,240,862, I have described a machine of this type.

exchangers and regenerator is constant and as this volume is interposed between the compression and expansion chambers, it comprises what might be considered a clear- .30 ance volume and it is obvious that to obtain l\any great amount of refrigeration this volume must. be small as compared to the piston displacement. Further a large surface area must be presented to the air to transfer the heat to or from it.

The object of my invention is to produce a heat exchanger that will contain a small volume of air, that will present a large surface to the air, that will be easy and cheap to manufacture and that will effectively transfer the heat from one. fluid to the other, and which, at the same time, will have a minimum number of joints to be kept tight between the two fluids.

I accomplish this object by constructing my heat exchangers with two annular chambers having one wall in common. In each chamber, I provide a number of metallic leaves which extend away from 'the wall across the chambers. -In this way a large l .surface is presented by the extended surfaces of the leaves and heat is readily absorbed from thel fluid while at the same time heat is conductedv through` the. leaves to `the' wall, through the Wall, and into the leaves As the volume ofthe air spaces in the heat on ythe other side of the wall, where it is given up to the other fluid circulating over those leaves.

, In order that my invention may be readily understood, it is described in connection with the accompanying drawings, Iin whichp Figure 1 is a vertical, longitudinal section of my air refrigerating machine, of which heat exchangersl according to this invention form a part.

Figure 2 is a plan view of the member containingthe heat exchanger for removing heat from the compressed air, with the upper part broken away for part of the circumference.

Figure 3 is an enlarged horizontal fragmental section of the heat exchanger taken on lines 3-3 of Figure 1.

Figure 4 is an enlarged vertical section taken on lines 4 4 ofFigure 2.

Referring to Figure '1, the. operation of the machine is as follows for one revolution of the crank shaft, the movements of the pistons being controlled by the mechanism in the crank case. y

The air is compressed between compression piston 1 and shifter piston 2. It is then transferred through annular port 3, the spaces between leaves 4 of heat exchanger 5, the regenerator 6 and the spaces between leaves 7 of'heat exchanger 8 to the space above Ythe piston 2 where it is expanded. The air is then transferred back again at the lower pressure tothe space between the two pistons 1 and 2 through the heat exchanger 8, regenerator 6 and heat exchanger 5.

In the heat exchanger 5, the warm compressed air gives up its heat to the leaves 4 which convey the heat to the wall 9 through which it is. transmitted to the leaves 10. Leaves 10 are surrounded by a cooling fluid such as water, which circulates from the annular chamber 11, over the leaves 10 and into the annular chamber 12. Pipe connections 25 and 26 (Figure 4) serve to carry the. cooling fluid to and 'from the chambers 11 and 12. In the heat exchanger 8, the cold expanded air absorbs heat from the leaves 7, to which the heat has been brought through the wall 13 from the leaves 14,. which in turn have been heated by the fluid circulating over them. This fluid may be any fluid as for example brine, which it is desired to refrigerate and it may enter the y out of the machine through pipe 16 to some chamber cool.- Y

Heat exchangers 5 and 8 closely resemble each other in construction, so the details will be described in connection with one of them, heatexchanger 5. Between the vertical wall 9 of an annular inverted U-shaped member 17 and an inner cylinder 18 are arranged a large number of channel shaped leaves `4 so made that their sides are on radial lines (see Figures 2 and 3). The

(not shown) which it is desired to leaves 4 are preferably of copper or other good heat conducting metal and may be i formed by rolling to shape and subsequently cutting ofi to the proper length. A One edge ofeah of the leaves 4 contacts with the wall 9 and the other edge with the cylindrical member 18. The spaces formed in the leaves 4 afford the path for the mediating air, and in machines I have constructed the dimensions of these spaces, in cross-section, are not more than .O15 inch by 9/32 inch, while the length of the channel shaped leaves in the directionof flow ,of the air is but one'inch. As illustrated in Figure 2, there are three hundred and sixty leaves each covering one degree of the circumference.

On the outer side of wall 9, there is closely fitted a cylindrical member 19 preferably of brass or other good heat conducting material. .Slots are milled vertically in member 19 and leaves 10 are secured in the` slotsA by suitable means such as sweating them in with solder. Member. 19 is used to facilitate construction, but it. may be omitted and the leaves 10 be secured directly y to wall 9. The number of leaves 10 and against leakage.

their size depend on the fluidused for cooling. If the fluid be water, an amount of surface relatively small compared to the surface of the leaves 4 is required. In any event,'the required surface is easily attained as the limitations of fiuid volume imposed in connection with leaves 4 do not apply to the spaces surrounding leaves 10. The

thickness of leaves 4 and 10 is chosen so that their conductivity in proportion to their heat absorbing power is such that all parts of the leaves will be at approximately the The inner wall of the.

cylinder 18 fits' snugly over the cylinder liner 24. The regenerator 6 is applied to the top of heat exchanger 5 in such a way that the opening-into it registers with the leaves 4 and its walls make tight joints with the wall 9 and cylinder liner 24. The heatexehangers of the other cylinder o'f the machine of Figure 1 are the .same as those of the cylinder described. i

.From the description it is seen that there is a wall separating the twofiuids between which it is desired to exchange heat and that there are but four joints to maintain tight against' leakage. These four joints are all lcircular and flat, hence easy to pack. lt is also to be noted that a large area is presented to the fluids with a minimum volume of metal and fluid. As the speed of the machine may bevas high as two hundred and fifty revolutions per minute, a complete cycle of operations takes place in less than one-quarter second, and the novel features of my invention render it possible to produce a commercial machine that is compact, efficient and economical to operate.

I claim 1. An annular heat exchanger adapted to be fitted onto a cylinder, comprising in combination a cylindrical wall of heat conductive material, heat conducting vanes extending outwardly `from said wall, and heat laid conducting vanes having flanges against the inner surface of the wall and extending inwardly therefrom, the inner ends of the vanes provided with means for closing the spaces between them.

2.. A heat exchanger'comprising in combination a cylinder, a piston moving therein to compress a -fluidat one end of the cylinder and rarefy it at the other end, annular heat exchangers, one at each end of the cylinder, each exchanger having a dividing wall forming interior and exterior annular spaces and conducting leaves in both spaces mounted on the common dividing wall, and an .annular packing sealing the joints between the cylinder and the heat exchangers.

3. A heat exchanger comprising in combination a' cylindrical wall enclosing an annular chamber forming a portion of the path for a mediating fluid, a second annular chamber surrounding said first cylindrical wall and adapted lto contain a fluid with which heat is exchanged, a series of flanged metallic leaves disposed in Vcontact withv each other completely around said first named annular chamber and in heat conductive relation at their edges with the wall separating the two annular chambers and a plurality of metallic leaves in said second annular chamber in heat conductive relation at their edges with said wall.

IVAR LUND GAARD. 

